Tail water system of pumped storage power station

Abstract

The utility model belongs to the technical field of pumped storage power stations, and particularly relates to a tail water system of a pumped storage power station. The tailrace tunnel comprises a tailrace tunnel lower flat section, a connecting well and a tailrace tunnel upper flat section which are sequentially arranged from the upstream end to the downstream end of the tailrace tunnel, the upstream end of the tailrace tunnel upper flat section is higher than the downstream end of the tailrace tunnel lower flat section, and the connecting well is a vertical shaft or an inclined shaft. The upper end of the connecting well is in smooth transition connection with the upstream end of the tailrace tunnel upper flat section through a tailrace tunnel first arc connecting section, and a tailrace surge shaft is arranged at the top of the tailrace tunnel first arc connecting section and composed of a surge chamber upper shaft and a surge chamber lower plugging section. And the surge chamber lower plugging section is provided with an impedance hole for communicating the bottom of the surge chamber upper shaft with the top of the first circular arc connecting section of the tailrace tunnel. The connecting well in the tail water surge chamber and the connecting well in the tail water tunnel are combined and arranged in the same area, so that arrangement and construction conditions are simplified.

Description

Technical Field

[0001] This utility model belongs to the technical field of pumped storage power stations, and specifically relates to a tailrace system of a pumped storage power station. Background Technology

[0002] The tailrace surge chamber is a key facility in the water conveyance system of a pumped storage project. Its necessity can be initially determined based on the value of the tailrace flow inertial time constant (Tws), and ultimately verified through hydraulic transition process calculations. The primary function of the tailrace surge chamber is to prevent liquid column separation within the tailrace pipe. The control index for its hydraulic transition process calculation is the maximum vacuum degree at the inlet of the tailrace pipe (i.e., the main tunnel of the tailrace tunnel). According to relevant specifications, if the maximum vacuum degree at the tailrace pipe inlet is no greater than 8m of water column, a tailrace surge chamber is not required. In high-head or ultra-high-head pumped storage power stations, this condition requires a sufficiently short tailrace tunnel. If the layout cannot meet this requirement, a tailrace surge chamber is necessary. If the tailrace tunnel length also does not meet the "one-slope-to-the-end" layout condition, a connecting shaft (inclined or vertical shaft) must be used in the middle of the tailrace tunnel for connection. This results in two separate well excavations for the tailrace surge chamber and the connecting shaft, making the tailrace system construction relatively complex. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a tailrace system for pumped storage power stations that simplifies layout and construction conditions.

[0004] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a tailrace system of a pumped storage power station, including a tailrace branch pipe located downstream of the power plant, the downstream end of the tailrace branch pipe connecting to a tailrace tunnel, the downstream end of the tailrace tunnel connecting to the inlet and outlet of the lower reservoir, the tailrace tunnel including a lower horizontal section, a connecting well, and an upper horizontal section arranged sequentially from its upstream end to its downstream end, the upstream end of the upper horizontal section of the tailrace tunnel being higher than the downstream end of the lower horizontal section of the tailrace tunnel, the connecting well being a vertical or inclined well, the upper end of the connecting well being smoothly connected to the upstream end of the upper horizontal section of the tailrace tunnel through a first arc connecting section of the tailrace tunnel, a tailrace surge tank being provided at the top of the first arc connecting section of the tailrace tunnel, the tailrace surge tank being composed of an upper cylinder of a surge tank and a lower sealing section of a surge tank, the lower sealing section of the surge tank being provided with an impedance hole connecting the bottom of the upper cylinder of the surge tank and the top of the first arc connecting section of the tailrace tunnel.

[0005] A further preferred embodiment is: the axis of the impedance hole is set vertically, the axis of the impedance hole is set eccentrically relative to the axis of the upper shaft of the pressure regulating chamber, and the impedance hole is set on the side of the first arc connecting section of the tailrace tunnel near the upstream end of the upper horizontal section of the tailrace tunnel.

[0006] A further preferred option is that the top of the upper shaft of the pressure regulating chamber is connected to a tailrace traffic tunnel.

[0007] A further preferred option is that the downstream end of the tailrace tunnel's lower horizontal section and the lower end of the connecting shaft are smoothly connected via the second circular arc connecting section of the tailrace tunnel.

[0008] A further preferred option is that, in the direction from the upstream end to the downstream end of the tailrace tunnel, the flow surfaces of both the lower horizontal section and the upper horizontal section of the tailrace tunnel adopt a reverse slope structure.

[0009] Compared with the prior art, the beneficial effects of this utility model are as follows: the tailrace surge chamber (i.e., the tailrace surge well set in this utility model) and the connecting well in the tailrace tunnel are combined and arranged in the same area, and the impedance hole at the bottom of the tailrace surge well is used to suppress the fluctuation amplitude of the water level in the surge chamber, accelerate the attenuation of the water level fluctuation, reduce the risk that the end of the upper horizontal section of the tailrace tunnel does not meet the minimum head design requirements, save the amount of engineering work, and have certain engineering economic benefits. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the elevation layout structure of this utility model.

[0011] Figure 2 for Figure 1 A magnified view of point C.

[0012] Figure 3 for Figure 2 Schematic diagram of section aa.

[0013] Figure 4 for Figure 2 A schematic diagram of the bb cross-section.

[0014] The components in the diagram are marked as follows: Power plant 1, tailrace branch pipe 2, tailrace tunnel 3, lower reservoir inlet / outlet 4, tailrace surge tank 5, lower horizontal section of tailrace tunnel 301, connecting well 302, upper horizontal section of tailrace tunnel 303, upper shaft of surge tank 501, impedance hole 502, and tailrace traffic tunnel 503. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0016] Please see Figures 1 to 4This utility model includes a tailrace branch pipe 2 located downstream of the power plant 1. The downstream end of the tailrace branch pipe 2 connects to the tailrace tunnel 3, and the downstream end of the tailrace tunnel 3 connects to the inlet / outlet 4 of the lower reservoir. The tailrace tunnel 3 includes a lower tailrace tunnel section 301, a connecting well 302, and an upper tailrace tunnel section 303 arranged sequentially from its upstream end to its downstream end. The upstream end of the upper tailrace tunnel section 303 is higher than the downstream end of the lower tailrace tunnel section 301. The connecting well 302... The tailrace tunnel can be a vertical or inclined shaft. The upper end of the connecting shaft 302 is smoothly connected to the upstream end of the upper horizontal section 303 of the tailrace tunnel via the first arc connecting section of the tailrace tunnel. A tailrace surge tank 5 is provided at the top of the first arc connecting section of the tailrace tunnel. The tailrace surge tank 5 consists of an upper shaft 501 of the surge tank and a lower sealing section of the surge tank. The lower sealing section of the surge tank is provided with an impedance hole 502 that connects the bottom of the upper shaft 501 of the surge tank and the top of the first arc connecting section of the tailrace tunnel. Specifically, the positions of the tailrace surge tank 5 and the connecting shaft 302 can refer to the conventional tailrace surge tank location in the prior art, and are located closer to the tailrace branch pipe 2. That is, the length of the lower horizontal section 301 of the tailrace tunnel is much smaller than the length of the upper horizontal section 303 of the tailrace tunnel. The lower sealing section of the surge tank typically employs a concrete backfill structure. This concrete backfill forms impedance holes 502, which suppress fluctuations in the surge tank water level and accelerate the attenuation of these fluctuations. This reduces the risk that the end of the upper horizontal section 303 of the tailrace tunnel (i.e., the end connecting the inlet / outlet 4 of the lower reservoir) may not meet the minimum head design requirement (generally not less than 2m). The tailrace surge tank 5 and the connecting well 302 in the tailrace tunnel 3, combined in this invention, are arranged in the same area, significantly reducing the amount of engineering work required.

[0017] To further mitigate the risk of the tailrace tunnel's upper horizontal section 303 failing to meet the minimum head design requirements, this invention may also employ the following preferred scheme: the axis of the impedance hole 502 is vertically oriented, eccentrically positioned relative to the axis of the upper shaft 501 of the surge chamber, and located on the side of the first arc-shaped connecting section of the tailrace tunnel near the upstream end of the upper horizontal section 303. The downstream end of the lower horizontal section 301 of the tailrace tunnel and the lower end of the connecting shaft 302 are smoothly connected via the second arc-shaped connecting section of the tailrace tunnel. In the direction from the upstream end to the downstream end of the tailrace tunnel 3, the flow surfaces of both the lower horizontal section 301 and the upper horizontal section 303 of the tailrace tunnel adopt a reverse slope structure. The upper shaft 501 of the pressure regulating chamber can be implemented with reference to existing technology. It generally adopts a circular cross section. In order to facilitate the normal operation of the pressure regulating chamber, the top of the upper shaft 501 of the pressure regulating chamber is generally connected to the tail flow tunnel 503.

[0018] The design elevation and inner diameter parameters of the upper shaft 501 of the surge chamber and the impedance orifice 502 can be matched to the actual working conditions. Specifically, in the preferred embodiment shown in the attached figure, the inner radius R1 of the upper shaft of the surge chamber is calculated to meet the requirements of the stable cross-sectional area, the radius R2 of the impedance orifice is determined according to the calculated impedance orifice area, and R3 is the inner diameter of the tailrace tunnel cross-section. The top elevation B of the impedance orifice meets the requirement of being 3m above the lowest surge water level under the design conditions and 2m above the lowest surge water level under the check conditions, thereby ensuring that the minimum pressure at the top of the tunnel at the end of the upper horizontal section of the tailrace tunnel is not less than 2m water head. The top elevation A of the upper shaft of the surge chamber meets the requirement of being 1.0m above the highest surge water level under the design conditions and 0.5m above the highest surge water level under the check conditions.

Claims

1. A pumped storage power station tailrace system, comprising a tailrace bifurcation (2) arranged at a downstream side of a power house (1), a downstream end of the tailrace bifurcation (2) being connected to a tailrace tunnel (3), a downstream end of the tailrace tunnel (3) being connected to an intake and outlet of a lower reservoir (4), the tailrace tunnel (3) comprising, from an upstream end to a downstream end thereof, a tailrace tunnel lower horizontal section (301), a connecting shaft (302) and a tailrace tunnel upper horizontal section (303), a position of an upstream end of the tailrace tunnel upper horizontal section (303) being higher than a position of a downstream end of the tailrace tunnel lower horizontal section (301), the connecting shaft (302) being a vertical shaft or an inclined shaft, characterized in that: The upper end of the connecting shaft (302) is connected to the upstream end of the upper horizontal section (303) of the tail water tunnel through a first circular arc connecting section of the tail water tunnel, and the top of the first circular arc connecting section of the tail water tunnel is provided with a tail water surge shaft (5), which is composed of a surge chamber upper shaft (501) and a surge chamber lower blocking section. The surge chamber lower blocking section is provided with an impedance hole (502) connecting the bottom of the surge chamber upper shaft (501) and the top of the first circular arc connecting section of the tail water tunnel.

2. The pumped storage power plant tailrace system of claim 1, wherein: The axis of the impedance hole (502) is vertically arranged, and the axis of the impedance hole (502) is eccentrically arranged relative to the axis of the surge chamber upper shaft (501). The impedance hole (502) is arranged on one side of the first circular arc connecting section of the tail water tunnel close to the upstream end of the upper horizontal section (303) of the tail water tunnel.

3. The pumped storage power plant tailrace system of claim 1, wherein: The top of the surge chamber upper shaft (501) is connected with a tail water traffic tunnel (503).

4. The pumped storage power plant tailrace system of claim 1, wherein: The downstream end of the lower horizontal section (301) of the tail water tunnel is connected to the lower end of the connecting shaft (302) through a second circular arc connecting section of the tail water tunnel.

5. A pumped storage power plant tailrace system according to any one of claims 1 to 4, characterized in that: In the direction from the upstream end to the downstream end of the tail water tunnel (3), the flow surfaces of the lower horizontal section (301) of the tail water tunnel and the upper horizontal section (303) of the tail water tunnel are both inverse slope structures.

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